<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<script src="./ckeditor/ckeditor.js"></script>
	<style>
		.box {
			width: 300px;
			border: 1px solid red;
		}
	</style>
</head>
<body>
	<div class="box">
		<textarea name="" id="txt" cols="30" rows="10"></textarea>
	</div>
	
	<script>
		CKEDITOR.replace( 'txt' );

	</script>
</body>
</html>